The present invention relates to primary electrochemical cells and, in particular, relates to the reactivation of a primary electrochemical cell having an oxidizable active anode material; a cathode material selected from the group consisting of halogens and metal halides; an electrolytic solution between and in contact with the anode and cathode; and an ampule having a reactivation material contained therein immersed in the electrolyte.
Modern technology has placed increased emphasis on producing an electrochemical power source having improved reliability, light weight, small size, high power, and a relatively long or infinite shelf life. Power sources meeting these requirements find ready civilian and military applications in portable communication systems, in particular, systems which have short duty cycles, e.g., on for short periods of time and then kept inactive for very long periods of time.
Various high-voltage, high-energy density electrochemical cells have been the subject of recent investigations. Much of the work in this area has been involved with electrochemical cells having negative electrodes comprising highly reactive metals such as lithium. Work on electrolytes for lithium-based electrochemical power sources has progressed generally along two major lines: high temperature, inorganic molten salt electrolytes and organic solvent-based electrolytes. A cell which utilizes a molten salt electrolyte provides a chemically stable system in which strong oxidants such as chlorine can be used as cathodes. For example, a molten salt cell utilizing a lithium anode and chlorine cathode provides exceptionally high energy and power density making development of a practical cell with these materials of particular interest. The molten salt lithium/chlorine cell (having a lithium anode, chlorine cathode and molten salt, typically lithium chlorine, electrolyte) has many characteristics desirable in a high performance electrochemical cell. The anode is highly electropositive, the cathode is highly electronegative, the equivalent weight of the reaction production is low, and the anode, cathode and electrolyte conductivities are high.
In parallel with the development of lithium cells with molten salt electrolytes, lithium cells with nonhydroxylic organic solvents have been developed. These cells have been called "organic electrolyte cells", although typically they employ electrolytes consisting of inorganic salts in organic solvents. Cells of this type have the advantage of being operable at room temperature. However, chlorine itself and other strong oxidants can not be used as a cathode depolarizer with these solvents, since the solvents are oxidized by chlorine. Therefore, cells of this type will not provide an energy density as high as a lithium/chlorine cell.
In application Ser. No. 342,233, filed Mar. 16, 1973, now abandoned the continuation-in-part application of application Ser. No. 131,530, filed Apr. 5, 1971, both abandoned, there is described an electrochemical cell having an active anode material selected from a specified group of materials, including lithium, a halogen or metal halide cathode material, and an electrolyte containing phosphorous oxychloride as the solvent material and a solute, selected from a wide range of materials, dissolved in the phosphorous oxychloride. A further description of primary cells utilizing oxychloride or thionylhalide solvent is disclosed in U.S. Pat. No. 3,897,264, James A. Auborn on July 29, 1975.